A recent study conducted by the Carnegie Mellon Electricity Industry Center finds that "there is no evidence that membership in an RTO (Regional Transmission Organization) promoted the development of renewables."

The study goes on to say that when the variable of RTO participation was isolated from other factors (such as state requirements for renewable production), there was no relationship between RTOs and renewable energy development, and a "negative correlation" between RTOs and wind energy. The study was partially funded by the American Public Power Association's (APPA) Electric Market Reform Initiative (EMRI).

The study's conclusions contradict a February 2007 open letter to the Federal Energy Regulatory Commission (FERC) from 22 organizations, many of which are supporters of renewable energy, asserting that "independent regional transmission operators such as Regional Transmission Organizations (RTOs) and Independent System Operators (ISOs) not only can promote electric system reliability and wholesale competition, they can also facilitate renewable energy and demand response development."

The American Wind Energy Association (AWEA) responded to the study by approving a resolution supporting the preservation and expansion of competitive wholesale electricity markets and stating that it strongly supports the open letter to FERC.

AWEA also stated that "studies that rely only on statistics on extremely limited and incomplete data from the first 8 GW of an industry that will be much larger, and RTOs that only recently came into operation, are of limited value."